The present invention relates to sanitizing agricultural fields after crop harvest by thermal treatment, and more particularly to a novel method for rapidly igniting combustible residue material on a field.
In certain agricultural practices, it is necessary to thermally treat a field after crop harvest in order to prepare the field for subsequent agricultural use. For instance, in the production of grass seed crops, thermal treatment through the form of field burning is necessary in order to control weeds, insects, rodents and diseases. In addition, field burning adequately removes crop residue such as stalks remaining after crop harvest.
Thermal treatment has conventionally taken the form of open field burning in which ground fires are initiated and permitted, with some degree of control, to run their course over a field. This procedure results in unacceptable air quality due to low altitude smoke pollution. As a consequence, legislation has been enacted, for instance in Oregon, which severely limits open field burning. One substitute for open field burning has been the provision of machines which are operable for traveling over a field and initiating a fire. However, known machines are extremely costly and their useful life is relatively unknown because of the high temperatures under which they must operate. In addition, the machines operate at low speeds and hence field burning is burdensomely time consuming.
As an alternative to machine burning, it has also been proposed to decrease air degradation by providing a so-called "big burn" process. The big burn process contemplates rapidly burning a large area of a field so that a concentrated heat source results and gives sufficient buoyancy to smoke produced by the burning so that the smoke is rapidly expelled into the upper atmosphere. With the smoke located at a relatively high altitude, it will be subject to more rapid dissipation by winds and therefore alleviate air pollution problems in the lower atmosphere.
Of course, it can be appreciated that in order to effectuate a "big burn", it is necessary to rapidly ignite a large field area. One proposed solution has been to dispatch a battery of helicopters over a field and dispense fuel over the area to be burned. The fuel is simultaneously ignited and a helicopter, in effect, has a fire trailed behind it. Of course, it can be realized that this is an extremely dangerous procedure and prohibitively expensive. Another proposed solution has been to provide burning elements or igniters pulled by a group of radio-controlled tractors. This technique also is expensive and time consuming.
Accordingly, it is a general object of the present invention to provide a method for rapidly igniting combustible material over a predetermined area of a field which contemplates positioning a plurality of combustible elements at spaced-apart locations adjacent a first boundary of the predetermined area. Lines are extended from each element across the length or width of the field to a position adjacent to a second boundary. Each line is then advanced or drawn so that its associated element is moved substantially across the predetermined area from the first boundary to the second boundary. The result is that a field may be rapidly torched by an extremely simple method which ensures burning a large area so that a concentrated heat source is created.
Another object of the present invention is to provide a motive or power source such as a line takeup means positioned adjacent to the second boundary which is secured to the lines operable for drawing each line and its associated element toward the second boundary. The power source may, in one embodiment, include provision of winches which are operable for drawing in the lines at substantially equal rates. Thus, as the combustible elements are rapidly drawn across the field, at substantially equal rates, a large area of the field will be burned substantially simultaneously. As indicated previously, with torching of a substantially large area, smoke management becomes significantly more feasible.
These and additional objects and advantages of the present invention will be more clearly understood from a consideration of the drawings and the detailed description of the preferred embodiment.